| Principle:
Michelson laser interferometer with two Fabry-Perot cavities in the arms
and power recycling. |
| Arms length: |
3 kilometers |
| Vacuum tube: |
120 cm diameter, fully welded (no seal) |
| Vacuum
performance: |
| |
Pressure after baking at
150o C: |
< 10-9 mbar |
| |
hydrocarbons partial pressure |
10-13 mbar |
| Laser
and injection system: |
| |
Nd:YAG diode-pumped
laser at 1064 nm |
|
| |
Laser power: |
20 W |
| |
Mode cleaner: |
144 m long, 3 mirrors ring
cavity |
| |
Finesse of mode cleaner cavity |
1000 |
| |
Frequency stability |
< 10-4 Hz1/2 at 1 kHz |
| |
Relative Intensity Noise (RIN) |
< 10-7 at 1 kHz |
| |
Power Stored in Fabry-Perot
cavity: |
15 to 50 kW (depending of
finesse) |
| |
Power Stored in recycling cavity: |
1 kW |
| Optics |
| |
Main mirror substrates |
special “Virgo”
grade fused silica |
| |
absorption < 1 ppm/cm
|
| |
diameter 350mm |
| |
Reflective coatings |
absorption < 1ppm |
| |
Anti reflection coatings |
reflection < 0.1 % |
| |
Surface quality |
l/200 rms |
| |
Surface microroughness |
< 1 Angstrom |
| Suspensions |
|
Inverted pendulum
pre-isolator plus 6 passive stages. |
|
|
Active control on first and last stage and
on mirror. |
|
| |
Seismic attenuation |
10-11 at 10
Hz |
| |
rms mirror motion before locking:
|
<1 mm, < 0.1 mradian |
| |
Thermal stabilization |
+/- 0.1 degree C |
| Frequency
range |
10 Hz to 10 kHz |
| Sensitivity
|
h ~ 3 10-21
Hz-1/2 at 10 Hz |
| h
~ 3 10-23 Hz-1/2 at 1 kHz |
| Provision
for future implementation of signal recycling technique |
